Self-adaption Ta/TaC multilayer coating with fine grains: toward excellent corrosion resistance in aggressive environment

Zhu, Yebiao; Dong, Minpeng; Mao, Feixiong; Guo, Wuqian; Li, Jinlong; Wang, Liping

doi:10.1007/s10853-021-06178-5

Cited by 6 publications

(2 citation statements)

References 52 publications

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“…A similar analysis of the TaC core level spectra acquired at grazing emission (Figure ) indicates the presence of multiple Ta oxidation states associated with TaC at binding energies of 23.4 eV [4f 7/2 ] and 25.3 eV [4f 5/2 ] ,, and TaO 2 centered at 25.0 [4f 7/2 ] eV and 26.9 eV[4f 5/2 ] . The C 1s spectra in Figure b were deconvoluted into two components at 282.9 and 284.4 eV, which correspond to TaC , and graphitic C (sp 2 -C), ,,, respectively.…”

Section: Resultsmentioning

confidence: 71%

Niobium Carbide and Tantalum Carbide as Nitrogen Reduction Electrocatalysts: Catalytic Activity, Carbophilicity, and the Importance of Intermediate Oxidation States

Alhowity,

Balogun,

Ganesan

et al. 2024

ACS Appl. Mater. Interfaces

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Significant interest in the electrocatalytic reduction of molecular nitrogen to ammonia (the nitrogen reduction reaction: NRR) has focused attention on transition metal carbides as possible electrocatalysts. However, a fundamental understanding of carbide surface structure/NRR reactivity relationships is sparse. Herein, electrochemistry, DFTbased calculations, and in situ photoemission studies demonstrate that NbC, deposited by magnetron sputter deposition, is active for NRR at pH 3.2 but only after immersion of an ambient-induced Nb 2 O 5 surface layer in 0.3 M NaOH, which leaves Nb suboxides with niobium in intermediate formal oxidation states. Photoemission data, however, show that polarization to −1.3 V vs Ag/AgCl restores the Nb 2 O 5 overlayer, correlating with electrochemical measurements showing inhibition of NRR activity under these conditions. In contrast, a similar treatment of a sputter-deposited TaC sample in 0.3 M NaOH fails to reduce the ambient-induced Ta 2 O 5 surface layer, and TaC is inactive for NRR at potentials more positive than −1.0 V even though a significant cathodic current is observed. A TaC sample with surface oxide partially reduced by Ar ion sputtering in UHV prior to in situ transfer to UHV exhibits a restored Ta 2 O 5 surface layer after electrochemical polarization to −1.0 V vs Ag/AgCl. The electrochemical and photoemission results are in accord with DFT-based calculations indicating greater N�N bond activation for N 2 bound end-on to Nb(IV) and Nb(III) sites than for N 2 bound end-on to Nb(V) sites. Thus, theory and experiment demonstrate that with respect to NbC, the formation and stabilization of intermediate (non-d 0 ) oxidation states for surface transition metal ions is critical for N�N bond activation and NRR activity. Additionally, the Nb suboxide surface, formed by immersion in 0.3 M NaOH of ambient-exposed NbC, is shown to undergo reoxidation to catalytically inactive Nb 2 O 5 at −1.3 V vs Ag/AgCl, possibly due to hydrolysis or other, as yet not understood, phenomena.

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Section: Resultsmentioning

confidence: 71%

Niobium Carbide and Tantalum Carbide as Nitrogen Reduction Electrocatalysts: Catalytic Activity, Carbophilicity, and the Importance of Intermediate Oxidation States

Alhowity,

Balogun,

Ganesan

et al. 2024

ACS Appl. Mater. Interfaces

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“…Ta and W 4f core level spectra exhibit doublets of peaks in the binding energies 23.5 and 25.3, 24.5 and 26.4, 25.8 and 27.8, 27.2 and 29.3, 32.0 and 34.1 eV (figure 11(d)). The peaks at 23.5 and 25.3 are attributed to TaC [54], while the peaks at 32.0 and 34.1 are associated with WC [59]. The peaks at 27.2 and 29.3 eV ascribed to Ta 2 O 5 [58], suggest that the sample presents an oxidation.…”

Section: Characterization Of Tac-wc After Electric Arc Furnace and Me...mentioning

confidence: 96%

Mechanosynthesis of TaC-WC powders under environmental conditions and their consolidation via electric arc furnace

Vázquez-Pelayo,

Garcia-Mendoza,

Becerril-Juarez

et al. 2024

Mater. Res. Express

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In this study, tantalum carbide (TaC) was synthesized using an innovative approach that synergistically integrates mechanosynthesis and electric arc furnace processes. By employing high-energy ball-milling (HEBM) for 50 min under environmental conditions, TaC-WC powders were successfully synthesized, using a powder mixture of tantalum and carbon in a 1:1 stoichiometric ratio. This method yielded a composition of 72.5 wt.% TaC and 27.5 wt.% WC, with an average particle size of 0.7±0.3 µm. The use of an electric arc furnace led to the fabrication of a highly dense material with a relative density above 98%. Notably, WC derived from the mechanical milling material served as an effective sintering aid. X-ray photoelectron Spectroscopy (XPS) results indicated the formation of metal oxides on the surface of the sample, and despite the presence of these oxides, the density of the material remained uncompromised. Furthermore, X-ray diffraction (XRD) analysis after the electric arc furnace treatment demonstrated the preservation of the TaC and WC phases. Mechanical properties, including Vickers hardness, Young’s modulus and fracture toughness were 22.8±0.5 GPa under an applied load of 9.8 N, 539 GPa and 6.6 MPa m1/2, respectively. The results underscore a novel and efficient synthesis route for TaC-WC with enhanced mechanical properties and high density, which are crucial aspects for applications in ultra-high temperature ceramics.

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Strong Binding Between YSZ Ceramic and 304 Steel Induced by Explosive Shaping

Hu,

Chen,

Zhou

et al. 2024

Metall Mater Trans B

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Self-adaption Ta/TaC multilayer coating with fine grains: toward excellent corrosion resistance in aggressive environment

Cited by 6 publications

References 52 publications

Niobium Carbide and Tantalum Carbide as Nitrogen Reduction Electrocatalysts: Catalytic Activity, Carbophilicity, and the Importance of Intermediate Oxidation States

Niobium Carbide and Tantalum Carbide as Nitrogen Reduction Electrocatalysts: Catalytic Activity, Carbophilicity, and the Importance of Intermediate Oxidation States

Mechanosynthesis of TaC-WC powders under environmental conditions and their consolidation via electric arc furnace

Strong Binding Between YSZ Ceramic and 304 Steel Induced by Explosive Shaping

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